A record number of businesses in San Diego and Imperial counties and nationwide turned over employment records to Immigration and Customs Enforcement for audits last year, according to figures released Monday to U-T San Diego.

The agency, which is part of the Department of Homeland Security, audited 3,000 companies and issued administrative fines to 495 businesses for more than $12.4 million overall.

The figures for San Diego and Imperial counties were 151 companies audited and 10 that were fined a combined $173,800. Among those fined were a boat-cleaning outfit, an egg ranch and an aerospace company.

The reviews, called I-9 audits, have soared in the past five years. They are expected to be a major talking point in the renewed debate over immigration reform in Washington, D.C. Current proposals by lawmakers and President Barack Obama call for increased worksite enforcement, particularly focusing on hiring practices.

“Employers who build their business model upon an illegal workforce will be held accountable,” Derek Benner, special agent in charge for ICE’s Homeland Security Investigations in San Diego, said Monday.

His agency released data from the program in response to a U-T request for such information.

Companies are supposed to have an I-9 form on file for every employee.

After an ICE audit identifies potential unauthorized workers, the employer must give those individuals a chance to rectify their documentation. Dismissal is required if the necessary proof is not provided.

“We hope for compliance,” said Mike Carney, the agency’s deputy special agent in charge of homeland security investigations in San Diego. “But some employers don’t fill out I-9s and don’t take it seriously.”

ICE imposes administrative fines on companies that lack some I-9s or have wrongly filled out those forms.

If the agency’s audits reveal more than sloppy bookkeeping, such as knowingly hiring or employing unauthorized workers, the businesses involved could face criminal charges. Last year, three local companies together owed more than half a million dollars in such sanctions.

Immigration officials have conducted I-9 audits since 1986 as part of the immigration overhaul that Congress and President Ronald Reagan approved that year. Full record-keeping began in 2007, and the audits became a more central part of immigration enforcement in 2009 when the Obama administration revised its worksite strategy to home in on employers instead of employees.

The strategy allows ICE “to reduce the magnet” by going after those who provide jobs to unauthorized immigrants, said Tom Hinkles, the supervisory special agent who oversees the 15-member team conducting I-9 investigations in San Diego and Imperial counties.

Illegal hiring can benefit unscrupulous employers, who may pay unauthorized laborers less money while making them work more hours, Hinkles said. Other abuses range from not giving required safety equipment to employees to outright labor trafficking.

Hinkles said his team focuses on industries known for hiring unauthorized workers — including food service, agriculture and construction — as well as firms that work on military bases and directly on public infrastructure (trains, airports, power plants). In addition, ICE receives tips from other law-enforcement agencies, the public and even workers at companies with alleged violations.

“Our focus isn’t on the employees but on employers,” Carney said.

Still, he said, ICE does occasionally arrest unauthorized employees who are identified through an I-9 audit — sometimes at their home. Reasons for an arrest include work-related identity fraud, a previous deportation or a criminal record.

In San Diego and Imperial counties, the agency reviewed tens of thousands of I-9s last year. ICE did not have information on how many of those were found to be questionable, as some of the cases are ongoing.

U-T San Diego called the 10 companies facing administrative fines last year; eight of them refused or were unavailable for comment Monday.

Bill Rocco, owner of Aquarius Yacht Services in San Diego, said he was fined $13,744 because he could not find any of his employees’ I-9 forms. He said they were misplaced after his boat-maintenance company downsized offices about three years ago, but that he did eventually find them after ICE had finished its review.

During the audit, Rocco said he had his workers redo their I-9 forms. All of them were eligible to work in the U.S., he added.

A decade ago, he said, two of his workers were deported after being picked up by the U.S. Coast Guard.

“Since then I have been pretty vigilant about making sure I have legal workers,” said Rocco, who is in bankruptcy. “I wish they would have audited a few of my competitors because I know they have undocumented workers and I didn’t.”

In Escondido, TDG Aerospace, which provides design and engineering services to commercial airlines, was fined $15,427. The company basically “messed up” by not having some I-9 forms or filling them out inaccurately for its 15 employees, said Andrew Wagner, chief operating officer. All of those workers are authorized to work in this country, he added.

“Everything has been updated and submitted, but they don’t really care. They still handed out a fine,” Wagner said. “Going forward, there will be a little more diligence when we hire, going through the process and making sure whatever paperwork we can use is squirreled away somewhere.”